From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753645AbaFXOKl (ORCPT ); Tue, 24 Jun 2014 10:10:41 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:59969 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753224AbaFXOKk (ORCPT ); Tue, 24 Jun 2014 10:10:40 -0400 Date: Tue, 24 Jun 2014 10:10:28 -0400 From: Greg KH To: Mathias Nyman Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, dan.j.williams@intel.com, Julius Werner Subject: Re: [PATCH 3/5] usb: xhci: Correct last context entry calculation for Configure Endpoint Message-ID: <20140624141028.GA2844@kroah.com> References: <1403618059-24533-1-git-send-email-mathias.nyman@linux.intel.com> <1403619322-24704-1-git-send-email-mathias.nyman@linux.intel.com> <1403619322-24704-3-git-send-email-mathias.nyman@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1403619322-24704-3-git-send-email-mathias.nyman@linux.intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 24, 2014 at 05:14:42PM +0300, Mathias Nyman wrote: > From: Julius Werner > > The current XHCI driver recalculates the Context Entries field in the > Slot Context on every add_endpoint() and drop_endpoint() call. In the > case of drop_endpoint(), it seems to assume that the add_flags will > always contain every endpoint for the new configuration, which is not > necessarily correct if you don't make assumptions about how the USB core > uses the add_endpoint/drop_endpoint interface (add_flags only contains > endpoints that are new additions in the new configuration). > > Furthermore, EP0_FLAG is not consistently set in add_flags throughout > the lifetime of a device. This means that when all endpoints are > dropped, the Context Entries field can be set to 0 (which is invalid and > may cause a Parameter Error) or -1 (which is interpreted as 31 and > causes the driver to keep using the old, incorrect value). > > The only surefire way to set this field right is to also take all > existing endpoints into account, and to force the value to 1 (meaning > only EP0 is active) if no other endpoint is found. This patch implements > that as a single step in the final check_bandwidth() call and removes > the intermediary calculations from add_endpoint() and drop_endpoint(). > > Signed-off-by: Julius Werner > Signed-off-by: Mathias Nyman > --- > drivers/usb/host/xhci.c | 51 +++++++++++++++++-------------------------------- > 1 file changed, 18 insertions(+), 33 deletions(-) Is this something for older (i.e. stable) kernels? thanks, greg k-h